I'd
like to follow up on the case-insensitivity issue and mention what I see as a
reasonable example that would argue against case-insensitivity. In my
experience, the vast majority of my accounts/login IDs on various systems are
case sensitive. Also, in unix-based systems (and many others),
most identifiers (anything in the file system for sure) are case
sensitive. If any of these identifiers are to be used in XRIs,
the case-sensitivity would need to be maintained, or ambiguity would be
introduced.

Between this issue and the Unicode issue, it seems to
me that it would be a bad idea to try to make any part of an XRI case
insensitive.

Case insensitivity is a form of normalization that a large population
of people receive benefit from. If there's a way to provide that
benefit to those people without degrading functionality where it doesn't make
sense, then I think we should do it.

I do
not think that there is a good way of introducing “case insensitivity” to
Unicode in general.

Case
insensitivity is a form of normalization, which is very problematic for the
international character set. IMHO, only meaningful form of general
equivalence is the bit to bit comparison or the comparison of the resolved
result from the same authority.